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-rw-r--r--kernel/cgroup.c114
-rw-r--r--kernel/cgroup_freezer.c24
2 files changed, 89 insertions, 49 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index d56d9363d4b3..15c93f9c9e57 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -367,9 +367,11 @@ static struct cgrp_cset_link init_cgrp_cset_link;
static int cgroup_init_idr(struct cgroup_subsys *ss,
struct cgroup_subsys_state *css);
-/* css_set_lock protects the list of css_set objects, and the
- * chain of tasks off each css_set. Nests outside task->alloc_lock
- * due to cgroup_iter_start() */
+/*
+ * css_set_lock protects the list of css_set objects, and the chain of
+ * tasks off each css_set. Nests outside task->alloc_lock due to
+ * cgroup_task_iter_start().
+ */
static DEFINE_RWLOCK(css_set_lock);
static int css_set_count;
@@ -394,10 +396,12 @@ static unsigned long css_set_hash(struct cgroup_subsys_state *css[])
return key;
}
-/* We don't maintain the lists running through each css_set to its
- * task until after the first call to cgroup_iter_start(). This
- * reduces the fork()/exit() overhead for people who have cgroups
- * compiled into their kernel but not actually in use */
+/*
+ * We don't maintain the lists running through each css_set to its task
+ * until after the first call to cgroup_task_iter_start(). This reduces
+ * the fork()/exit() overhead for people who have cgroups compiled into
+ * their kernel but not actually in use.
+ */
static int use_task_css_set_links __read_mostly;
static void __put_css_set(struct css_set *cset, int taskexit)
@@ -2982,10 +2986,10 @@ int cgroup_task_count(const struct cgroup *cgrp)
}
/*
- * To reduce the fork() overhead for systems that are not actually
- * using their cgroups capability, we don't maintain the lists running
- * through each css_set to its tasks until we see the list actually
- * used - in other words after the first call to cgroup_iter_start().
+ * To reduce the fork() overhead for systems that are not actually using
+ * their cgroups capability, we don't maintain the lists running through
+ * each css_set to its tasks until we see the list actually used - in other
+ * words after the first call to cgroup_task_iter_start().
*/
static void cgroup_enable_task_cg_lists(void)
{
@@ -3199,11 +3203,15 @@ css_next_descendant_post(struct cgroup_subsys_state *pos,
}
EXPORT_SYMBOL_GPL(css_next_descendant_post);
-/*
- * Advance a list_head iterator. The iterator should be positioned at
- * the start of a css_set
+/**
+ * cgroup_advance_task_iter - advance a task itererator to the next css_set
+ * @cgrp: the cgroup to walk tasks of
+ * @it: the iterator to advance
+ *
+ * Advance @it to the next css_set to walk.
*/
-static void cgroup_advance_iter(struct cgroup *cgrp, struct cgroup_iter *it)
+static void cgroup_advance_task_iter(struct cgroup *cgrp,
+ struct cgroup_task_iter *it)
{
struct list_head *l = it->cset_link;
struct cgrp_cset_link *link;
@@ -3223,7 +3231,21 @@ static void cgroup_advance_iter(struct cgroup *cgrp, struct cgroup_iter *it)
it->task = cset->tasks.next;
}
-void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it)
+/**
+ * cgroup_task_iter_start - initiate task iteration
+ * @cgrp: the cgroup to walk tasks of
+ * @it: the task iterator to use
+ *
+ * Initiate iteration through the tasks of @cgrp. The caller can call
+ * cgroup_task_iter_next() to walk through the tasks until the function
+ * returns NULL. On completion of iteration, cgroup_task_iter_end() must
+ * be called.
+ *
+ * Note that this function acquires a lock which is released when the
+ * iteration finishes. The caller can't sleep while iteration is in
+ * progress.
+ */
+void cgroup_task_iter_start(struct cgroup *cgrp, struct cgroup_task_iter *it)
__acquires(css_set_lock)
{
/*
@@ -3236,11 +3258,20 @@ void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it)
read_lock(&css_set_lock);
it->cset_link = &cgrp->cset_links;
- cgroup_advance_iter(cgrp, it);
+ cgroup_advance_task_iter(cgrp, it);
}
-struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
- struct cgroup_iter *it)
+/**
+ * cgroup_task_iter_next - return the next task for the iterator
+ * @cgrp: the cgroup to walk tasks of
+ * @it: the task iterator being iterated
+ *
+ * The "next" function for task iteration. @it should have been
+ * initialized via cgroup_task_iter_start(). Returns NULL when the
+ * iteration reaches the end.
+ */
+struct task_struct *cgroup_task_iter_next(struct cgroup *cgrp,
+ struct cgroup_task_iter *it)
{
struct task_struct *res;
struct list_head *l = it->task;
@@ -3254,16 +3285,25 @@ struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
l = l->next;
link = list_entry(it->cset_link, struct cgrp_cset_link, cset_link);
if (l == &link->cset->tasks) {
- /* We reached the end of this task list - move on to
- * the next cg_cgroup_link */
- cgroup_advance_iter(cgrp, it);
+ /*
+ * We reached the end of this task list - move on to the
+ * next cgrp_cset_link.
+ */
+ cgroup_advance_task_iter(cgrp, it);
} else {
it->task = l;
}
return res;
}
-void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it)
+/**
+ * cgroup_task_iter_end - finish task iteration
+ * @cgrp: the cgroup to walk tasks of
+ * @it: the task iterator to finish
+ *
+ * Finish task iteration started by cgroup_task_iter_start().
+ */
+void cgroup_task_iter_end(struct cgroup *cgrp, struct cgroup_task_iter *it)
__releases(css_set_lock)
{
read_unlock(&css_set_lock);
@@ -3312,7 +3352,7 @@ static inline int started_after(void *p1, void *p2)
* Iterate through all the tasks in a cgroup, calling test_task() for each,
* and if it returns true, call process_task() for it also.
* The test_task pointer may be NULL, meaning always true (select all tasks).
- * Effectively duplicates cgroup_iter_{start,next,end}()
+ * Effectively duplicates cgroup_task_iter_{start,next,end}()
* but does not lock css_set_lock for the call to process_task().
* The struct cgroup_scanner may be embedded in any structure of the caller's
* creation.
@@ -3333,7 +3373,7 @@ static inline int started_after(void *p1, void *p2)
int cgroup_scan_tasks(struct cgroup_scanner *scan)
{
int retval, i;
- struct cgroup_iter it;
+ struct cgroup_task_iter it;
struct task_struct *p, *dropped;
/* Never dereference latest_task, since it's not refcounted */
struct task_struct *latest_task = NULL;
@@ -3368,8 +3408,8 @@ int cgroup_scan_tasks(struct cgroup_scanner *scan)
* guarantees forward progress and that we don't miss any tasks.
*/
heap->size = 0;
- cgroup_iter_start(scan->cgrp, &it);
- while ((p = cgroup_iter_next(scan->cgrp, &it))) {
+ cgroup_task_iter_start(scan->cgrp, &it);
+ while ((p = cgroup_task_iter_next(scan->cgrp, &it))) {
/*
* Only affect tasks that qualify per the caller's callback,
* if he provided one
@@ -3402,7 +3442,7 @@ int cgroup_scan_tasks(struct cgroup_scanner *scan)
* the heap and wasn't inserted
*/
}
- cgroup_iter_end(scan->cgrp, &it);
+ cgroup_task_iter_end(scan->cgrp, &it);
if (heap->size) {
for (i = 0; i < heap->size; i++) {
@@ -3608,7 +3648,7 @@ static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
pid_t *array;
int length;
int pid, n = 0; /* used for populating the array */
- struct cgroup_iter it;
+ struct cgroup_task_iter it;
struct task_struct *tsk;
struct cgroup_pidlist *l;
@@ -3623,8 +3663,8 @@ static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
if (!array)
return -ENOMEM;
/* now, populate the array */
- cgroup_iter_start(cgrp, &it);
- while ((tsk = cgroup_iter_next(cgrp, &it))) {
+ cgroup_task_iter_start(cgrp, &it);
+ while ((tsk = cgroup_task_iter_next(cgrp, &it))) {
if (unlikely(n == length))
break;
/* get tgid or pid for procs or tasks file respectively */
@@ -3635,7 +3675,7 @@ static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
if (pid > 0) /* make sure to only use valid results */
array[n++] = pid;
}
- cgroup_iter_end(cgrp, &it);
+ cgroup_task_iter_end(cgrp, &it);
length = n;
/* now sort & (if procs) strip out duplicates */
sort(array, length, sizeof(pid_t), cmppid, NULL);
@@ -3669,7 +3709,7 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
{
int ret = -EINVAL;
struct cgroup *cgrp;
- struct cgroup_iter it;
+ struct cgroup_task_iter it;
struct task_struct *tsk;
/*
@@ -3683,8 +3723,8 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
ret = 0;
cgrp = dentry->d_fsdata;
- cgroup_iter_start(cgrp, &it);
- while ((tsk = cgroup_iter_next(cgrp, &it))) {
+ cgroup_task_iter_start(cgrp, &it);
+ while ((tsk = cgroup_task_iter_next(cgrp, &it))) {
switch (tsk->state) {
case TASK_RUNNING:
stats->nr_running++;
@@ -3704,7 +3744,7 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
break;
}
}
- cgroup_iter_end(cgrp, &it);
+ cgroup_task_iter_end(cgrp, &it);
err:
return ret;
@@ -5137,7 +5177,7 @@ void cgroup_fork(struct task_struct *child)
* Adds the task to the list running through its css_set if necessary and
* call the subsystem fork() callbacks. Has to be after the task is
* visible on the task list in case we race with the first call to
- * cgroup_iter_start() - to guarantee that the new task ends up on its
+ * cgroup_task_iter_start() - to guarantee that the new task ends up on its
* list.
*/
void cgroup_post_fork(struct task_struct *child)
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index 98ca48d9ceb4..c9177f8fc661 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -258,7 +258,7 @@ static void update_if_frozen(struct cgroup_subsys_state *css)
{
struct freezer *freezer = css_freezer(css);
struct cgroup_subsys_state *pos;
- struct cgroup_iter it;
+ struct cgroup_task_iter it;
struct task_struct *task;
WARN_ON_ONCE(!rcu_read_lock_held());
@@ -279,9 +279,9 @@ static void update_if_frozen(struct cgroup_subsys_state *css)
}
/* are all tasks frozen? */
- cgroup_iter_start(css->cgroup, &it);
+ cgroup_task_iter_start(css->cgroup, &it);
- while ((task = cgroup_iter_next(css->cgroup, &it))) {
+ while ((task = cgroup_task_iter_next(css->cgroup, &it))) {
if (freezing(task)) {
/*
* freezer_should_skip() indicates that the task
@@ -296,7 +296,7 @@ static void update_if_frozen(struct cgroup_subsys_state *css)
freezer->state |= CGROUP_FROZEN;
out_iter_end:
- cgroup_iter_end(css->cgroup, &it);
+ cgroup_task_iter_end(css->cgroup, &it);
out_unlock:
spin_unlock_irq(&freezer->lock);
}
@@ -323,25 +323,25 @@ static int freezer_read(struct cgroup_subsys_state *css, struct cftype *cft,
static void freeze_cgroup(struct freezer *freezer)
{
struct cgroup *cgroup = freezer->css.cgroup;
- struct cgroup_iter it;
+ struct cgroup_task_iter it;
struct task_struct *task;
- cgroup_iter_start(cgroup, &it);
- while ((task = cgroup_iter_next(cgroup, &it)))
+ cgroup_task_iter_start(cgroup, &it);
+ while ((task = cgroup_task_iter_next(cgroup, &it)))
freeze_task(task);
- cgroup_iter_end(cgroup, &it);
+ cgroup_task_iter_end(cgroup, &it);
}
static void unfreeze_cgroup(struct freezer *freezer)
{
struct cgroup *cgroup = freezer->css.cgroup;
- struct cgroup_iter it;
+ struct cgroup_task_iter it;
struct task_struct *task;
- cgroup_iter_start(cgroup, &it);
- while ((task = cgroup_iter_next(cgroup, &it)))
+ cgroup_task_iter_start(cgroup, &it);
+ while ((task = cgroup_task_iter_next(cgroup, &it)))
__thaw_task(task);
- cgroup_iter_end(cgroup, &it);
+ cgroup_task_iter_end(cgroup, &it);
}
/**
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-02 22:15:36 +0000